Oltipraz (RP 35972) is a synthetic dithiolethione with potential chemopreventive and anti-angiogenic properties. Oltipraz induces phase II detoxification enzymes, such as glutathione S transferase (GST) and NAD(P)H: quinone oxidoreductase 1 (NQO1). The induction of detoxification enzymes enhances the detoxification of certain cancer-causing agents, thereby enhancing their elimination and preventing carcinogen-induced DNA damages. Although the exact mechanism through which the anti-angiogenesis effect remains to be fully elucidated, oltipraz maybe able to modulate the expression of a number of angiogenic factors, thereby blocking the sustained and focal neovascularization in multiple tumor cell types.